Telephone communication has seen a phenomenal growth since its inception because of its extreme usefulness in today's world. It is hard, and almost impossible, to conceive of a world without telephones. Telephones have become an integral part of a civilized society. Modern telephones include generic desk-top telephone units, cordless telephones and more advanced cellular telephones (or “cell phones”). In contrast to a cordless telephone unit, a cellular telephone allows portability in that a cell phone operator can use the cell phone many miles away from home and the use is supported by a sophisticated telecommunications system.
Because a cell phone imparts mobility to the user while on the phone, quick detection of the location of the cell phone is important in the event of fraud or when there is a need to locate a cellular telephone (and, hence, its user) that placed a phone call for emergency assistance, e.g., a “911 call.” It is also desirable to locate the cell phone operator or mobile subscriber (MS) for marketing reasons, e.g., for targeting location-specific advertisements to the cell phone operator upon determining the location of the cell phone operator. For example, one or more stores in a shopping complex (e.g., a mall) may wish to inform the cell phone operator about any current promotions or offers when the cell phone operator is found to be in the vicinity of the shopping complex.
In a cellular telephone network operated by a wireless service provider (SP), a mobile switching center (MSC) may serve more than one cell-site. Therefore, to locate a cellular phone within the network, a switch engineer may need to manually visit the MSC location and identify the cell-site within which the cellular phone is operative. Such a process may not be efficient when there are a large number of cell phone operators and in the event of frequent fraudulent or “911” calls. Further, it is also possible that the cell phone operator may swiftly change cells if the detection of the cell phone location takes more than a few minutes and especially when the cell phone operator is located near a cell boundary. In such an event, the earlier cell identification may prove wrong and the whole process may be repeated to identify the new cell site to which the cell phone operator has moved.
It is known to locate a cellular telephone having a predetermined telephone number by using time difference of arrival measurements (on signals transmitted from the specific cell phone) at a multiplicity of cell-phone base-stations. However, a GPS (Global Positioning System) antenna and a corresponding GPS receiver need to be added to each base station for use in locating the cell phone in this manner.
It is also known to locate the source of radio transmissions (including cellular phone transmissions) within a multipath signal environment. A hand-held sensor unit with a built-in non-directional or omnidirectional antenna can be used to capture signal transmissions from the source of radio transmissions to be located. Phase change measurements and other calculations are performed during processing of the captured signals and the signal-emitting source (e.g., a cell phone) is then located based on the outcome of the processing.
Furthermore, the identity of the cell phone operator may already be known to the wireless service provider serving the cell phone. For example, the wireless service provider may request information about the identity of the mobile subscriber (e.g., name, gender, age, employment information, etc.) when the mobile subscriber signs up to operate the cell phone in the wireless service provider's network. In another configuration, the identity of the cell phone operator may be available to an Internet world wide web advertiser with the help of, for example, cookies. The web advertiser may employ cookies to store information about and preferences of individual mobile subscribers who access particular websites on the Internet using web browser-equipped cell phones. It is known that cookies are digital text files placed in the cell phone's memory by a web server when the cell phone operator visits a web site served by the web server. Cookies are commonly used to store registration data such as the user's (here, the mobile subscriber's) name and address, the user's preferences, and so on. Cookies make it possible for web servers to personalize information to fit the user's specific needs and preferences when the user is visiting a web site on the Internet.
A wireless service provider may wish to supply a mobile subscriber's location information to a third party (e.g., a web advertiser) as part of the service provider's marketing activity. Also, a web advertiser (or any other marketing entity) may send location-specific advertisements to a mobile subscriber upon being informed of the current location of the subscriber. Because of various reasons (e.g., privacy concerns), it may be desirable that the wireless service provider not disclose the mobile subscriber's identity to the third party when sending the subscriber's location information to the third party. It may also be desirable that the web advertiser not transmit the mobile subscriber's identity information when communicating with the mobile subscriber over the Internet.
Alternatively, it may be desirable that the wireless service provider block the mobile subscriber's location information while supplying the subscriber's identity information to a third party. For example, a cell phone operator may wish to receive operator-specific advertisements over the cell phone from the third party without having the third party know of the physical location of the operator. Similarly, it may further be desirable that the web advertiser block any reference to the mobile subscriber's current physical location when sending any subscriber-specific advertisements to the mobile subscriber over the Internet. It may also be desirable for any other (i.e., non-Internet) advertiser to not disclose the cell phone operator's current location in or through the messages communicated between the advertiser and the cell phone.